The the art, the analysis of fluid suspensions containing toxic materials always required prior knowledge of the specific nature of the material to be detected. This is not always possible. On a battlefield, no one knows what he will encounter.
Further, toxic entities can exist as complex mixtures. It would take many time-consuming steps just to detect what toxic material is present. Rapid detection of the presence of toxic materials is a problem which continues to exist, whenever the battlefield is considered.
Hazard avoidance, or corrective action, could benefit from an assay which indicates the presence of a particular class of toxic materials in fluids. The assay should not have to depend on prior knowledge of the specific nature of the toxic materials encountered in the field.
In the art, U.S. Pat. No. 4,447,546 and U.S. Pat. No. 4,558,014 describe assays of optically dense materials by sampling fluids. However, again, prior knowledge of the specific nature of the toxic material to be identified is necessary. For example, such assays rely on a particular antibody to bind a specific antigen, and vice-versa.